1. Field of the Invention
The present application relates in general to the field of rotor systems for rotorcraft.
2. Description of Related Art
There are many different types of rotorcraft, including helicopters, tandem rotor helicopters, tiltrotor aircraft, four-rotor tiltrotor aircraft, tilt wing aircraft, and tail sitter aircraft. In all of these rotorcraft, thrust and/or lift is generated by air flowing through a rotor disk formed by a plurality of rotating rotor blades. The plurality of rotor blades are mechanically coupled with and substantially evenly spaced about a rotatable mast, which provides rotational motion to the plurality of rotor blades. Each of the plurality of rotor blades is independently rotatable to affect a pitch of the blade. Varying the pitch of the plurality of blades affects lift and the direction of thrust produced by the rotating plurality of blades.
FIG. 1 depicts a military tiltrotor aircraft 101 with conventional rotor hubs 107a and 107b. Rotor hubs 107a and 107b are mechanically coupled to nacelles 103a and 103b, respectively. Nacelles 103a and 103b are rotably attached to wing members 105a and 105b, respectively. Wing members 105a and 105b are rigidly fixed to fuselage 109. Rotor hubs 107a and 107b have a plurality of rotor blades 111a and 111b, respectively. The tiltrotor aircraft 101 of FIG. 1 is depicted in helicopter mode, with nacelles 103a and 103b directed up.
FIG. 2 depicts a commercial tiltrotor aircraft 201 with conventional rotor hubs 207a and 207b. Rotor hubs 207a and 207b are mechanically coupled to nacelles 203a and 203b, respectively. Nacelles 203a and 203b are rotably attached to wing members 205a and 205b, respectively. Wing members 205a and 205b are rigidly fixed to fuselage 209. Rotor hubs 207a and 207b have a plurality of rotor blades 211a and 211b, respectively. FIG. 2 depicts tiltrotor aircraft 201 in airplane mode, with nacelles 203a and 203b directed forward.
It is often desirable to utilize a multiple rotor disks in a stacked configuration, the multiple rotor disks rotating about the same axis of rotation, to increase the lift and/or thrust of a rotorcraft. In operation, each rotor disk may experience a different aerodynamic condition, depending on variables such as forward speed and orientation of the rotor hub. There is a need for rotor system which can variably adjust the pitch of the rotor blades of each rotor disk in a simple and efficient means.
There are many rotorcraft rotor systems well known in the art; however, considerable room for improvement remains.
While the system and method of the present application is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the application to the particular embodiment disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the process of the present application as defined by the appended claims.